March 17, 2010 -
The FAA has issued a Special Airworthiness Information Bulletin (SAIB)
advising the owners and operators of general aviation (GA) aircraft of
an airworthiness concern, specifically the need to inspect properly and
maintain the exhaust system to prevent carbon monoxide leakage into the
cabin and to install a commercially available carbon monoxide detector
in the cabin.

This revision adds
the Federal Aviation Administration (FAA) TechnicalCenter library website and revises the
recommendation section. At this time, this airworthiness concern is not
considered an unsafe condition that would warrant an airworthiness
directive action under Title 14 of the Code of Federal Regulations (14
CFR), part 39.

This SAIB is in
response to a National Transportation Safety Board (NTSB) investigation
of an accident on December 17, 2000, where a
Beech Model BE-23 aircraft impacted terrain killing the
commercial-rated pilot, the sole occupant of the airplane. The NTSB
determined the probable cause of the accident was in part “the pilot’s
incapacitation due to carbon monoxide (CO) and a fractured muffler.”

The report shows that 43 commercially available CO detectors, sampled
from each of the five sensor technology types (biometric,
electrochemical, spot, infrared, and semiconductor) were surveyed to
determine the most appropriate sensor technology. The electrochemical
sensor-based CO detectors were found to be most suitable for use in the
GA environment. Limited field testing using portable electrochemical CO
detectors was conducted in two GA aircraft models to determine the best
location for a CO detector.

Based on the analyses of collected CO data, the instrument panel
appeared to be the best location for the placement of CO detectors. The
report notes that, to increase the probability of being able to detect
at least 50 parts per million (PPM) anywhere in the cabin, the CO
detector should be set at a lower alarm threshold of 35 PPM. Performance
parameters and specifications of various CO detectors (available on the
market) were compiled into a database as shown in Tables B-2 through B-5
of the technical report.

Recommendation

The FAA recommends
that you do the following:

1. Consider the
information in the technical report, and use a CO detector while
operating your aircraft.

2. To detect
leakage of gases into the cabin due to cracks in the exhaust system,
conduct engine run up tests with cabin heat on and check for CO in the
cabin with a hand-held CO detector during 100 hour and annual
inspections.

3. Continue to
inspect the complete engine exhaust system during 100 hour/annual
inspections and at inspection intervals recommended by the aircraft and
engine manufacturers in accordance with their applicable maintenance
manual instructions.